The present invention relates to an elevating apparatus or lift for elevating a lifting table or platform to lift workers and/or materials to higher places for assembly, painting, repair or various other labor activities.
There have heretofore been used elevating apparatus for elevating a lifting table or platform to lift workers and/or materials to higher places for assembly, painting, repair in various locations such as construction sites, highways, and other areas requiring work at elevated levels. Such conventional elevating apparatus include scissors-type lifts in the form of a pantograph comprising a plurality of vertically connected X-shaped arms with two arms in each X-shaped arm unit being centrally pivotally interconnected. However, in order to raise the lifting table to a higher position, the number of X-shaped arm units has to be increased. This has led to problems in that the collapsed lift has an increased height, and workers will encounter difficulty in getting on and off the platform and in loading and unloading materials onto and from the platform. To avoid such drawbacks, there has been proposed an elevating apparatus having an extensible and contractable arm assembly accommodating a plurality of telescopic booms that the arm assembly can longitudinally be extended and contracted. With this proposed elevating apparatus, two booms are combined into a centrally pivoted X-shaped boom assembly, and two of such boom assemblies are disposed parallel to each other on mobile chassis, the mobile chassis and the platform being interconnected by four upper and lower arms. Since the number of the booms used is large, the elevating apparatus is complex in structure, cannot easily be assembled, and is expensive to manufacture. The booms and arms are held in sliding contact with each other through sliders of synthetic resin such as MC nylon, which are required to be replaced at regular intervals. As a consequence, it is costly and time-consuming to inspect and service the elevating apparatus constructed of telescopic booms.